Gender‐specific neuromuscular adaptations to unloading in isolated rat soleus muscles

: The potential of gender to affect unloading‐induced neuromuscular adaptations was investigated. Methods : Twenty male and 20 female rats were assigned to control (CTL), or unloaded (UL) conditions. After 2 weeks of unloading, soleus muscles were removed, and neuromuscular function was assessed during a train of alternating indirect (neural) and direct (muscle) stimuli. Results : In rested muscle, strength showed significant ( P ≤ 0.05) main effects for gender (male > female) and treatment (CTL > UL). By the end of the testing protocol, when muscles showed fatigue, gender‐related and treatment‐related differences in strength had disappeared. Neuromuscular transmission efficiency and strength suffered a greater decline during the testing protocol in males than females. Unloaded male muscles displayed greater contractile velocity than female muscles both when rested and fatigued. Conclusions : Gender affected unloading‐induced neuromuscular adaptations. The greater strength of rested male muscles was due to greater muscle mass and neuromuscular transmission efficiency. Muscle Nerve 54 : 300–307, 2016